Input vs output token spend
Output tokens usually cost several times more than input, so answer length is what really drives your bill.
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AI & LLM Cost
OpenAI API Cost Calculator
Estimate your OpenAI bill in seconds. Choose a GPT model, enter your request volume and token sizes, and see the monthly cost with a comparison across the whole OpenAI lineup for 2026.
Estimated monthly cost
$0
Cost per request—
Cost per 1,000 requests—
Input token cost—
Output token cost—
Tokens processed / month—
Annual estimate—
The same workload priced across AI models
Your monthly token volume run through popular 2026 models, cheapest first.
What the OpenAI API Cost Calculator does
OpenAI bills its API per token, with a separate rate for input and output on each model. The lineup spans from the tiny, cheap GPT-5 nano through GPT-5 mini and the flagship GPT-5, plus GPT-4.1, GPT-4o and the o-series reasoning models. Picking the right tier for each job is the main way to control an OpenAI bill.
This OpenAI API cost calculator prices your workload on the model you choose and compares it against every current OpenAI model, so you can see when GPT-5 mini would carry the load at a fraction of GPT-5 cost, or when a reasoning model is worth its premium.
Heads up on pricing. The rates built into this tool are public list estimates for July 2026 and can change without notice. Providers also offer batch discounts, prompt caching and volume tiers that lower real costs, so treat the output as a planning estimate, not a quote.
The formula
cost = (input tokens ÷ 1M × input rate) + (output tokens ÷ 1M × output rate)
GPT-5: $1.25 input, $10 output per million tokens
GPT-5: $1.25 input, $10 output per million tokens
Worked example
On GPT-5, 100,000 requests a month at 1,000 input and 500 output tokens cost 100M × $1.25 + 50M × $10 per million = $125 + $500 = about $625 a month. Switching to GPT-5 mini drops that to roughly $125.
OpenAI API pricing used (per 1M tokens, July 2026 estimates)
| Model | Input / 1M | Output / 1M |
|---|---|---|
| GPT-5 | $1.25 | $10.00 |
| GPT-5 mini | $0.25 | $2.00 |
| GPT-5 nano | $0.05 | $0.40 |
| GPT-4.1 | $2.00 | $8.00 |
| GPT-4o | $2.50 | $10.00 |
| OpenAI o3 | $2.00 | $8.00 |
| OpenAI o4-mini | $1.10 | $4.40 |
July 2026 list estimates. OpenAI also offers cached input at a large discount and batch pricing at half rate, which can cut real costs significantly.
Ways to lower your AI costs
- Match the model to the task. Route simple requests to a small model like GPT-5 mini, Gemini Flash or DeepSeek V3, and keep premium models for complex reasoning where quality pays off.
- Cache repeated context. Prompt caching means you stop paying full price for the same system prompt or documents on every call.
- Cap output length. Output tokens cost several times more than input, so limiting response length is often the fastest saving you can make.
- Trim prompts and history. Summarize old conversation turns and drop context the model does not actually need to answer well.
- Batch non-urgent work. Many providers offer batch pricing at around half the standard rate for jobs that can wait a few hours.
Frequently asked questions
How much does the OpenAI API cost in 2026?
GPT-5 is about $1.25 per million input tokens and $10 output. Smaller models like GPT-5 mini and nano cost far less. Enter your usage above for a monthly total.
What is the cheapest OpenAI model?
GPT-5 nano is the cheapest at roughly $0.05 input and $0.40 output per million tokens, ideal for simple, high volume tasks.
Does OpenAI offer discounts?
Yes. Cached input tokens cost much less, and the Batch API runs non-urgent jobs at about half price. Both can meaningfully lower your bill.
How are o-series reasoning models priced?
They bill per token like other models, but they generate hidden reasoning tokens that count as output, so complex prompts can cost more than the visible answer suggests.
Are these rates official?
They are July 2026 list estimates for planning. Check the OpenAI pricing page for the current official rates.